1. Field
Embodiments relate to a wireless power transfer system.
2. Background
A wireless power transfer (WPT) system is a technology for transferring power without wires through a space, and maximizes the convenience of power supply to mobile devices and digital home appliances.
The WPT system has advantages such as saving energy through real-time power usage control, overcoming space limit of power supply, reducing waste battery discharge using battery recharging, and the like.
As a method of implementing the WPT system, there are typically a magnetic induction method and a magnetic resonance method.
The magnetic induction method is a noncontact energy transfer technique in which two coils are brought close to each other to cause a current to be supplied to one coil and an electromotive force is generated in the other coil via a magnetic flux generated in accordance with the current, and uses frequencies of hundreds of kHz.
The magnetic resonance method is a magnetic resonance technique using only an electric field or a magnetic field without using electromagnetic waves or current, and has a distance enabling power transfer of several meters or more, so that it uses a band of tens of MHz.
Meanwhile, in the WPT system, A4WP that is a resonant wireless charging standard occupies an industrial scientific and medical (ISM) band using Bluetooth communication. However, since the ISM band has been already used as communication frequencies (wireless LAN (WLAN), Bluetooth, Zigbee, RFID, etc.) of a lot of wireless communication, there has been a problem that deteriorates the performance of wireless communication devices using the nearby ISM band at the time of wireless charging.